This invention relates to a new general aerodynamic concept for high-subsonic large civil and military aircraft with a goal to drastically reduce fuel consumption at high subsonic speed and significantly increase lift capacity and range of aircraft relatively to existing classical concept aircraft with simultaneous reduction in external dimensions of aircraft, as well as reduction in runway length in order to utilize existing airport facilities. The new concept simultaneously provides for significantly better stability, maneuverability, and safety relatively to the existing concepts based on the idea of tailless flying wing.
Increase in air traffic volume and very dynamic development thereof have set very challenging goals with respect to moving ever larger payloads safely at large distances as fast as possible at low cost. The former goals have generated very intense research efforts and development of new aerodynamic concepts, materials, and new energy sources.
At the beginning of the 20th century, the classical concept of aircraft had been established based on three basic premises: aircraft wings to generate necessary lift, tail surfaces for pitch and yaw control and fuselage unit with the purpose to connect wings and tail surfaces into one piece and provide space for payload accommodation. The relatively simple cigar-like fuselage shape is favorable from the aspect of passenger area pressurization, simple adjustments of wing and tail positions relatively to gravity center with the purpose of providing for a good stability and maneuverability of aircraft. All of this resulted in prevailing dominance of this concept for an entire century. The response to requirements for lower fuel consumption, high speed, and longer range was sought mainly in development of new and more efficient airfoils, redesign of transitional surfaces between fuselage and aerodynamic surfaces to increase aerodynamic efficiency, as well as in development of new materials and more efficient engines. The results of this search did not fully meet market demands so that in the past two to three decades the solutions for reduction of transportation cost have been sought by increasing payload capacity and thereby the external dimensions of aircraft, which resulted in significant increase of parasitic drag of fuselage with wing spans reaching critical size that limits maneuver of aircraft on the ground. It is obvious today that further significant advances in payload increase and reduction of air transportation cost is only possible with new aircraft concepts by significantly reducing already drastically increased fuselage parasitic drag.
The ideas to eliminate fuselage parasitic drag date back to 1930s when attempts were made to shape aircraft fuselage as an airlifting surface. All previous ideas and inventions can be categorized in two groups:                a) Separately shaped fuselages as airlifting surfaces        b) Total integration of payload space with wings into a single airlifting surface called “flying wing” or “flying body”The following U.S. patents fit into the first category: 1,893,129; 2,123,096; 2,557,962; 2,616,639; 3,216,673; 3,869,102; 6,098,922; 6,606,406.        
U.S. Pat. Nos. 2,557,962; 3,216,673 and 6,666,406 refer to methods to shape only the central fuselage section or a part thereof into a single aerodynamic surface wherein two lateral fuselages are preserved to which wings and tail surfaces are connected. Very complex configuration of these aircraft generates high interference drag between aircraft sections. Simultaneously, the central section with relatively thick airfoils generates high airfoil drag especially at high flight speed. These solutions can contribute to increase in payload capacity of aircraft to some extent. However, the aerodynamic efficiency of these aircraft is significantly lower when compared to modern aircraft with classical design concept. Also, manufacturing costs would be significantly higher for these aircraft.
U.S. Pat. No. 1,893,129 anticipates a central section of the wing with elongated chords that is used as a fuselage. The leading edge of the central section and external wings intersects each other in a point, thereby preventing generation of induced drag on the leading edge. The central section is separated from external wings by a vertical aerodynamic former, which behind external wings performs as both a winglet to reduce the generation of induced drag in the rear portion of the central section, as well as a fin with rudder.
U.S. Pat. No. 2,123,096 anticipates a similar solution as in U.S. Pat. No. 1,893,129, however, with the shape of aerodynamic formers being somewhat changed between the central section and external wings. The basic shortcoming of both of these patents is insufficient longitudinal stability and pitch maneuver.
The following U.S. patents, publications, and projects full into the second category: U.S. Pat. Nos. 2,294,367, 2,402,358, 2,406,506, 2,412,646, 2,650,780, 3,576,300, 3,761,041, 4,149,688, 5,082,204, 6,578,798; Model 1 and Model 2 published in French Journal Air & Cosmos No. 1386 in 1992 (attached in the patent application); BWB (Blended Wing Body) project.
U.S. Pat. Nos. 2,294,367 and 2,402,358 depict fuselages as rectangular shaped wings with a relatively low wing aspect ratio that generate high induced drag and have insufficient longitudinal stability and pitch maneuver.
U.S. Pat. Nos. 2,406,506; 2,412,646 and 2,650,780 show classical “Flying Wing” concepts with short chords, low sweep angle of wings, and thick airfoils in the payload area, which generate high airfoil drag, while relatively low wing sweepback angle does not provide for a sufficient longitudinal stability and pitch maneuver of the aircraft.
U.S. Pat. No. 3,576,300 anticipates a “Flying Wing” concept with a delta shape and high sweep angle of the leading edge that results in low wing aspect ratio where jet engine air inlets are disposed on the upper surface of the central section in order to reduce the thickness of the boundary layer thereof. Low aspect ratio of the wings results in insufficient roll maneuver and generates high induced drag, which reduces aerodynamic efficiency that was achieved by boundary layer control in the area of jet engines air inlets. In addition, the distribution of craft weight and aerodynamic surfaces does not provide for sufficient longitudinal stability and pitch maneuver of the aircraft.
U.S. Pat. Nos. 3,761,041 and 4,149,688 disclose “Flying Body” concepts with horizontal and vertical stabilizing surfaces disposed on the trailing edge of the flying body. Very low wing aspect ratio of the fling body as an airlifting surface generates very high induced drag, while very small stabilizing surfaces with their short distance from the gravity center do not provide for required level of roll and pitch maneuver, as well as the longitudinal stability of the craft.
U.S. Pat. No. 5,082,204 anticipates a “Flying Wing” concept with a very complex trailing edge shape where both front and aft surfaces thereof are in the area of the central section. The aft surfaces of this craft improve longitudinal stability thereof when compared to the classical “Flying Wing” concept with a relatively low sweepback angle. However, the interference drag, especially in the area of front and aft surfaces is very high, while short airfoil chords do not provide for a sufficient space for payload accommodation when relatively thin airfoils are used.
Model 1 (Air and Cosmos Magazine, No. 1386 of 1992) represents a “Flying Body” concept with a delta form, as well as a convexly shaped leading edge and straight-line trailing edge that include additional tail surfaces (vertical and horizontal) to increase longitudinal stability, as well as pitch and yaw maneuver. This concept provides for the formation of significant space for payload accommodation with relatively thin airfoils. The low wing aspect ratio of this body generates high induced drag and results in insufficient roll maneuver control capability of the craft. A small surface area of the tailplane compared to main body surface area and a relatively short distance between the tail surface and gravity center of the aircraft does not provide for a sufficient longitudinal stability and pitch maneuver thereof.
Model 2 (Air and Cosmos Magazine, No. 1386 of 1992) represents a combination of “Flying Body” and classical concepts where external wings are integrated with the flying body on the trailing edge thereof. This concept provides for a good roll and pitch maneuver control as well as sufficient longitudinal stability of the aircraft but generates a significant parasitic drag in the frontal area that produces a very low lift, while the middle section with a low span generates high induced drag. Complex aerodynamic shape in the area between front and aft section of the aircraft would represent challenges during the manufacturing process.
BWB Project represented one of the latest serious attempts to apply the “Flying Wing” idea on the large Jumbo Jet subsonic aircraft. This project was based on the idea to minimize the size of aerodynamic surfaces that are exposed to airflow in order to achieve a minimum friction drag by eliminating fuselage and tail surfaces with the entire surface of the aircraft generating lift, while span and airfoil chords of the external wings are designed to minimize induced drag to the highest extent possible. Having this principle as guidance, the project got into serious troubles related to insuring sufficient space for payload accommodation by using relatively thin airfoils, while the wingspan reached proportions that are very close to limiting the maneuver of such aircraft on existing airports. The problem with shortage of space for payload accommodation was attempted to be resolved by increasing the relative thickness of the airfoils in the payload area, which increased drag and significantly reduced aerodynamic efficiency especially at high subsonic speed. Another problem is related to insufficient longitudinal stability and maneuver control of the aircraft that is required for civil aircraft, which is the key shortcoming of this concept.
U.S. Pat. No. 6,578,798 discloses a “Flying wing” concept with added aft aerodynamic surfaces for the longitudinal stabilization of aircraft, which were created as the result of the division of aerodynamic surfaces on their external ends. This concept resolved the problem of payload accommodation by using airfoils with relatively low thickness, as well as the problem related to longitudinal stability and maneuver control requirements. A shortcoming of this concept is unfavorable vertical position of the aft stabilizing aerodynamic surfaces relatively to the external wings that are positioned in front of them. The stabilizing surfaces are disposed aft of and below external wings, which would significantly reduce their efficiency and thereby flight safety during takeoff and landing when the flaps of the external wings are deflected downwardly. Another shortcoming of this idea is related to increased drag due to significant deformation of the under surface in the area of airlifting surface division.